Problem reading burnt DVD's or CD's by my DVD-RW drive

I burnt couple of DVD’s and CD’s recently and then tried to open them again at a later date, but when I open the drive directory, I don’t get anything in it. I know there is something in these DVD/CD’s because a friend of mine has used it successfully. So it has to be a problem with my DVD ROM. I have a sony vaio, and my DVD is TOSHIBA DVD-ROM SD-R6012.

I am stuck for a lot of my important back ups happen to be in this DVD and I really need to retrieve it.

Any ideas?

Some DVD-ROMs simply won’t read some types of burned DVDs. Though it’s pretty puzzling that it does not read the burned CD.